(a) Technical Field
The present disclosure relates to a thin film transistor array panel for a liquid crystal display and to a manufacturing method thereof.
(b) Description of the Related Art
A liquid crystal display (LCD) typically includes a pair of display panels having field generating electrodes, polarizers and a liquid crystal layer interposed between the two display panels. A field-generating electrode generates an electric field on the liquid crystal layer. Furthermore, as the intensity of the electric field changes, the arrangement of liquid crystal molecules varies as well. For example, when an electric field is generated, liquid crystal molecules of a liquid crystal layer change their arrangement to thereby also change the polarization of light passing through the liquid crystal layer. In addition, the polarizer of the LCD blocks or transmits the polarized light appropriately to make bright and dark regions, thereby causing desired images to be displayed.
The LCD includes, for example, a display panel which includes a plurality of pixels having switching elements, a plurality of display signal lines, and a gate driver having a plurality of stages transmitting gate signals to gate lines of the display signal lines to turn on/off the switching elements of the pixels.
Each stage of the gate driver is connected to one of the signal lines. The stages receive gate on/off voltages clock signals and transmit the inputted gate on/off voltages and clock signals to the signal line connected thereto.
The gate driver may be integrated with the substrate, and then the gate lines may extend to be connected to the gate driver directly. In this situation to connect the gate wires of the gate driver and the data wires of the gate driver, a contact hole exposing the gate wire is formed, and then the data wire is contacted to the data wire through the contact hole using a connecting member made of, for example, indium tin oxide (ITO).
Alternatively, if the gate driver is formed outside of the substrate, pad portions, which connect the gate on/off signal lines to the stages of the gate driver, are used for transmitting the gate on/off voltage to the stages of the gate driver. In this case, to connect the pad portions to the signal lines, contact holes exposing the signal lines are formed, and then the signal lines are contacted to the stages of the gate driver through the contact holes using a connecting member made of, for example, ITO.
Furthermore, as the lengths of the signal lines increase along with the size of the LCD, the resistance of the signal lines increases as well. Consequently, a signal delay or a voltage drop occurs due to the increased resistance of the signal lines. Thus, wiring made of a material having low resistivity, such as, for example aluminum (Al), should be utilized for the signal lines.
For example, when aluminum (Al) is used in wiring, signal lines may have a multi-layered structure including an Al layer and another layer.
However, if the signal lines including Al are contacted to ITO used in pixel electrodes or connecting members of an LCD directly, then Al may be oxidized or corroded.